Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

A touch panel includes a substrate, a touch sensing electrode, and an
optical compensation layer. The touch sensing electrode is disposed on
the substrate. The optical compensation layer is disposed on the
substrate and covers the touch sensing electrode. A refraction index of
the optical compensation layer is smaller than or equal to a refraction
index of the touch sensing electrode.

Claims:

1. A touch panel, comprising: a substrate; a touch sensing electrode,
disposed on the substrate; and an optical compensation layer, disposed on
the substrate and covering the touch sensing electrode, wherein a
refraction index of the optical compensation layer is smaller than or
equal to a refraction index of the touch sensing electrode.

2. The touch panel of claim 1, wherein the touch sensing electrode
comprises at least one first axis sensing electrode and at least one
second axis sensing electrode disposed on one identical surface of the
substrate, a refraction index of the first axis sensing electrode and the
second axis sensing electrode is between 1.7 and 2.0, and the refraction
index of the optical compensation layer is between 1.6 and 1.7.

3. The touch panel of claim 1, wherein the touch sensing electrode
comprises at least one first axis sensing electrode and at least one
second axis sensing electrode respectively disposed on two opposite
surfaces of the substrate, the optical compensation layer comprises a
first optical compensation layer and a second optical compensation layer
respectively covering the first axis sensing electrode and the second
axis sensing electrode, a refraction index of the first axis sensing
electrode and the second axis sensing electrode is between 1.7 and 2.0,
and a refraction index of the first optical compensation layer and the
second optical compensation layer is between 1.6 and 1.7.

4. The touch panel of claim 1, wherein the touch sensing electrode
comprises a thickness between 18 nanometers and 150 nanometers, and the
optical compensation layer comprises a thickness between 60 nanometers
and 150 nanometers.

5. The touch panel of claim 1, wherein the substrate includes a cover
lens or a cover glass.

6. The touch panel of claim 5, further comprising a decoration layer,
disposed on an edge of the substrate, wherein the decoration layer
comprises ceramic material, diamond like carbon material, color ink,
photo resist, or resin.

7. The touch panel of claim 1, further comprising an adhesive layer and a
covering substrate, wherein the adhesive layer is disposed on the optical
compensation layer, the covering substrate is disposed on the adhesive
layer, and a refraction index of the adhesive layer is smaller than the
refraction index of the optical compensation layer.

8. The touch panel of claim 3, further comprising two adhesive layers, a
covering substrate, and a protection layer, wherein the two adhesive
layers are respectively disposed on the first optical compensation layer
and the second optical compensation layer, and a refraction index of the
adhesive layers is smaller than the refraction index of the optical
compensation layer.

9. The touch panel of claim 6, further comprising an adhesive layer and a
protection layer, wherein the adhesive layer is disposed on the optical
compensation layer, the protection layer is disposed on the adhesive
layer, and a refraction index of the adhesive layer is smaller than the
refraction index of the optical compensation.

Description:

[0002] The present invention relates to a touch panel, and more
particularly, to a touch panel including an optical compensation layer to
improve an appearance quality of the touch panel.

[0003] 2. Description of the Prior Art

[0004] In recent years, touch sensing technologies have developed
flourishingly, and electronic products, such as mobile phones, tablet
PCs, GPS navigator systems, laptop PCs, and desktop PCs, which have both
the touch sensing function and the display function, are commercialized
accordingly. There are many diverse technologies of touch panel, such as
the resistance touch technology, the capacitive touch technology and the
optical touch technology which are the main touch technologies in use.
The capacitive touch technology has become the mainstream touch
technology for the high-end and the mid-end consumer electronics, because
the capacitive touch panel has advantages such as high precision,
multi-touch property, better endurance, and higher touch resolution.

[0005] In the capacitive touch technology, transparent sensing electrodes
are used to detect the variations of electrical capacitances around a
touch point, and feedback signals are transmitted via connecting lines,
which interconnect all of the transparent sensing electrodes along
different axis directions to locate the touch points. In the conventional
capacitive touch technology, the transparent sensing electrodes are made
of transparent conductive materials such as indium tin oxide (ITO) which
is a material with a high refractive index (about 1.7 to 2.0) but still
may absorb some light. Therefore, a visual difference may be generated
between a region with the transparent sensing electrodes and a region
without the transparent sensing electrodes, an issue of visible
transparent sensing electrodes may occur, and an appearance quality of
the touch panel may accordingly be affected. In addition, the issue of
visible transparent sensing electrodes may become more serious in large
size touch panels because a thickness of the transparent sensing
electrode has to be thicker to lower the total resistance for the driving
requirement. For example, when a size of the normal touch panel is larger
than 7 inches, the thickness of the transparent sensing electrode may
have to be thicker than 90 nanometers to lower the total resistance, and
the issue of visible transparent sensing electrodes may become more
serious. In the conventional capacitive touch panel, a silicon oxide
layer or an organic photo resist layer are generally used to cover the
transparent sensing electrode. Since a refraction index of the silicon
oxide layer or the organic photo resist layer of about 1.5 is apparently
different from the refraction index of ITO, the silicon oxide layer or
the organic photo resist layer may only be employed to protect or
insulate the transparent sensing electrode from other things, and the
issue of visible transparent sensing electrodes may not be improved with
the silicon oxide layer or the organic photo resist layer.

SUMMARY OF THE INVENTION

[0006] It is one of the objectives of the present invention to provide a
touch panel. An optical compensation layer is disposed in the touch
panel. Differences of refraction index and chromaticity between a region
with transparent sensing electrodes and a region without the transparent
sensing electrodes may become minor under interference of light, an issue
of visible transparent sensing electrodes in the touch panel may be
accordingly reduced and a transmittance of the touch panel may be
accordingly enhanced.

[0007] To achieve the purposes described above, a preferred embodiment of
the present invention provides a touch panel. The touch panel includes a
substrate, a touch sensing electrode, and an optical compensation layer.
The touch sensing electrode is disposed on the substrate. The optical
compensation layer is disposed on the substrate and covers the touch
sensing electrode. A refraction index of the optical compensation layer
is smaller than or equal to a refraction index of the touch sensing
electrode.

[0008] These and other objectives of the present invention will no doubt
become obvious to those of ordinary skill in the art after reading the
following detailed description of the preferred embodiment that is
illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 and FIG. 2 are schematic diagrams illustrating a touch panel
according to a first preferred embodiment of the present invention.

[0010]FIG. 3 is a schematic diagram illustrating a touch panel according
to a second preferred embodiment of the present invention.

[0011]FIG. 4 is a schematic diagram illustrating a touch panel according
to a third preferred embodiment of the present invention.

[0012] FIG. 5 is a schematic diagram illustrating a touch panel according
to a fourth preferred embodiment of the present invention.

[0013] FIG. 6 and FIG. 7 are schematic diagrams illustrating a touch panel
according to a fifth preferred embodiment of the present invention.

[0014]FIG. 8 is a schematic diagram illustrating a touch panel according
to a sixth preferred embodiment of the present invention.

DETAILED DESCRIPTION

[0015] Certain terms are used throughout the description and following
claims to refer to particular components. As one skilled in the art will
understand, electronic equipment manufacturers may refer to a component
by different names. This document does not intend to distinguish
components that differ in name but not function. In the following
description and in the claims, the term "include" is used in an
open-ended fashion, and thus should be interpreted to mean "include, but
not limited to . . . " In addition, to simplify the descriptions and make
it more convenient to compare embodiments between each other, identical
components are marked with the same reference numerals in each of the
following embodiments. Please note that the figures are only for
illustration and the figures may not be to scale. Additionally, the terms
such as "first" and "second" in this context are only used to distinguish
different components and do not constrain the order of generation.

[0016] Please refer to FIG. 1 and FIG. 2. FIG. 1 and FIG. 2 are schematic
diagrams illustrating a touch panel according to a first preferred
embodiment of the present invention. FIG. 1 is a top-view diagram. FIG. 2
is a cross-sectional view diagram taken along a cross-sectional line A-A'
in FIG. 1. Please note that the figures are only for illustration and the
figures may not be to scale. The scale may be further modified according
to different design considerations. As shown in FIG. 1 and FIG. 2, the
first preferred embodiment of the present invention provides a touch
panel 101. The touch panel 101 includes a substrate 110, a touch sensing
electrode 120, and an optical compensation layer 151. The touch sensing
electrode 120 is disposed on the substrate 110. More specifically, the
touch sensing electrode 120 in this embodiment includes a plurality of
first axis sensing electrodes 121 and a plurality of second axis sensing
electrodes 122. The first axis sensing electrodes 121 and the second axis
sensing electrodes 122 are disposed on a first surface 111 of the
substrate 110. In this embodiment, the first axis sensing electrodes 121
and the second axis sensing electrodes 122 are preferably made of a
transparent conductive material, such as indium tin oxide (ITO), indium
zinc oxide (IZO), or aluminum zinc oxide (AZO), but not limited thereto.
In addition, the touch sensing electrode 120 is not limited to a
structure of multi-layer transparent electrodes, such as the first axis
sensing electrodes 121 and the second axis sensing electrodes 122
mentioned above, and the touch sensing electrode 120 in this invention
may also be a structure of a single layer transparent electrode, and the
sensing electrode may include a diamond shape electrode, a triangle
electrode, a linear electrode, or other electrodes with irregular shapes.
The optical compensation layer 151 is disposed on the substrate 110 and
covers the touch sensing electrode 120, i.e. the optical compensation
layer 151 covers the first axis sensing electrodes 121 and the second
axis sensing electrodes 122. A refraction index of the optical
compensation layer 151 is smaller than or equal to a refraction index of
the touch sensing electrode 120. In other words, the refraction index of
the optical compensation layer 151 is smaller than or equal to a
refraction index of the first axis sensing electrodes 121 and the second
axis sensing electrodes 122. Additionally, the optical compensation layer
151 may include organic materials, such as polyimide (PI) and acrylic
resin, inorganic materials, such as titanium oxide, a single layer
structure of the above-mentioned materials, or a stack layer of the
above-mentioned materials, but the present invention is not limited to
this, and the optical compensation layer 151 may be further modified
according to different required refraction indexes. In this embodiment,
the optical compensation layer 151 may be formed by dry coating methods,
such as chemical vapor deposition (CVD), or wet coating methods, such as
spin on coating, but not limited thereto.

[0017] In this embodiment, the refraction index of the touch sensing
electrode 120 is substantially between 1.7 and 2.0, i.e. the refraction
indexes of the first axis sensing electrodes 121 and the second axis
sensing electrodes 122 are substantially between 1.7 and 2.0. The
refraction index of the optical compensation layer 151 is preferably
between 1.6 and 1.7. A thickness of the first axis sensing electrode 121
is substantially equal to a thickness of the second axis sensing
electrode 122, but not limited thereto. Additionally, a thickness of the
touch sensing electrode 120 is substantially between 18 nanometers and
150 nanometers, i.e. the thickness of the first axis sensing electrode
121 and the thickness of the second axis sensing electrode 122 are
respectively between 18 nanometers and 150 nanometers. A thickness of the
optical compensation layer 151 is between 60 nanometers and 150
nanometers. In other preferred embodiments of the present invention, the
thickness of the touch sensing electrode 120 may be larger than 90
nanometers, but not limited thereto. More specifically, a thickness of
the optical compensation layer 151 covering the first axis sensing
electrode 121 and a thickness of the optical compensation layer 151
covering the second axis sensing electrode 122 are preferably between 60
nanometers and 150 nanometers. A preferred optical effect may be
accordingly generated by controlling the thicknesses and the refraction
indexes described above. For example, please refer to Table 1 and FIG. 2.
Table 1 shows a transmittance of the touch panel 101, differences of
reflection rate, and color differences between a region with the first
axis sensing electrodes 121 and the second axis sensing electrodes 122
and a region without the first axis sensing electrodes 121 and the second
axis sensing electrodes 122 when the optical compensation layer 151 with
a refraction index equal to 1.65 is employed in the touch panel 101. In
addition, Table 1 also shows a transmittance of conventional touch panel
with a silicon oxide layer covering the sensing electrodes, differences
of reflection rate, and color differences between a region with the
sensing electrodes and a region without the sensing electrodes in the
conventional touch panel. A thickness T1 represents the thickness of the
first axis sensing electrode 121.

[0018] As shown in Table 1, when the optical compensation layer 151 with
the refraction index equal to 1.65 is employed in the touch panel 101,
the differences of reflection rate, and the color differences between the
region with the first axis sensing electrodes 121 and the second axis
sensing electrodes 122 and the region without the first axis sensing
electrodes 121 and the second axis sensing electrodes 122 may be
apparently improved. Therefore, the optical compensation layer 151 may be
employed to effectively overcome the issue of the visible transparent
sensing electrodes in the touch panel. Additionally, the transmittance of
the touch panel may also be enhanced by replacing the conventional
silicon oxide layer with the optical compensation layer 151 in the touch
panel.

[0019] Please refer to Table 2 and FIG. 2. Table 2 shows the differences
of reflection rate, and the color differences between the region with the
first axis sensing electrodes 121 and the second axis sensing electrodes
122 and the region without the first axis sensing electrodes 121 and the
second axis sensing electrodes 122 according to different exemplary
embodiments wherein optical compensation layers 151 with different
refraction indexes and thicknesses are respectively used. A thickness T1
stands for the thickness of the first axis sensing electrode 121, a
thickness T2 stands for the thickness of the optical compensation layer
151 covering the first axis sensing electrode 121, and a refraction index
N stands for the refraction index of the optical compensation layer 151.

[0020] As shown in Table 2, when the optical compensation layer 151 with
the refraction index equal to 1.65 or 1.70 is employed in the touch panel
101, the differences of reflection rate, and the color differences
between the region with the first axis sensing electrodes 121 and the
second axis sensing electrodes 122 and the region without the first axis
sensing electrodes 121 and the second axis sensing electrodes 122 may be
apparently improved. In addition, the thickness T2 of the optical
compensation layer 151 covering the first axis sensing electrode 121 is
preferably between 60 nanometers and 150 nanometers, but the present
invention is not limited to this, and the thickness of the optical
compensation layer 151 may be further modified according to the
refraction index and the thickness of the first axis sensing electrode
121 or the second axis sensing electrode 122. For instance, in the
exemplary embodiment 1 in Table 2, an optical compensation layer having a
thickness around 1200 nanometers and a refraction index around 1.7 may
also be employed to improve the differences of reflection rate and the
color differences.

[0021] As shown in FIG. 1 and FIG. 2, the touch panel 101 in this
embodiment may further include a first connecting line 141, a second
connecting line 142, and an insulating layer 130 disposed on the
substrate 110. The first connecting line 141 is employed to electrically
connect two adjacent first axis sensing electrodes 121, and the second
connecting line 142 is employed to electrically connect two adjacent
second axis sensing electrodes 122. The insulating layer 130 is disposed
between the first connecting line 141 and the second connecting line 142
so as to electrically insulate the first connecting line 141 from the
second connecting line 142. In this embodiment, the first connecting line
141 and the second connecting line 142 may include transparent conductive
materials such as indium tin oxide, indium zinc oxide, and aluminum zinc
oxide, or other appropriate non-transparent conductive materials such as
silver (Ag), aluminum (Al), copper (Cu), magnesium (Mg), molybdenum (Mo),
a stack layer of the above-mentioned materials, or an alloy of the
above-mentioned materials, but not limited thereto. The insulating layer
130 may include inorganic materials, such as silicon nitride, silicon
oxide, and silicon oxynitride, organic materials, such as acrylic resin,
or other appropriate insulating materials. Additionally, in this
embodiment, an insulating film (not shown) may also be selectively
disposed between the substrate 110 and the first axis sensing electrode
121 or between the substrate 110 and the second axis sensing electrode
122, or a transparent conductive shielding layer (not shown) and an
insulating film (not shown) may be selectively disposed on a second
surface 112 of the substrate 110 so as to improve touch operations on the
touch panel 101, but not limited thereto. In other embodiments of the
present invention, the second connecting line 142 may be formed in a
manufacturing process forming the first axis sensing electrode 121 and
the second axis sensing electrode 122. In other words, the second
connecting line 142 and two adjacent second axis sensing electrode 122
may be formed simultaneously and connected to each other, but the present
invention is not limited to this.

[0022] The following description will detail the different embodiments of
the touch panel in the present invention. To simplify the description,
identical components in each of the following embodiments are marked with
identical symbols. For making it easier to understand the differences
between the embodiments, the following description will detail the
dissimilarities among different embodiments and the identical features
will not be redundantly described.

[0023] Please refer to FIG. 3. FIG. 3 is a schematic diagram illustrating
a touch panel according to a second preferred embodiment of the present
invention. As shown in FIG. 3, the difference between a touch panel 102
of this embodiment and the touch panel 101 of the first preferred
embodiment is that the touch panel 102 further includes an adhesive layer
160 and a covering substrate 170 disposed on the substrate 110. In this
embodiment, the adhesive layer 160 is disposed on the optical
compensation layer 151, and the covering substrate 170 is disposed on the
adhesive layer 160. In other words, the adhesive layer 160 is disposed
between the covering substrate 170 and the optical compensation layer 151
so as to combine the covering substrate 170 and the optical compensation
layer 151. The optical compensation layer 151 is disposed between the
substrate 110 and the adhesive layer 160, and the optical compensation
layer 151 is disposed between the substrate 110 and the covering
substrate 170. The adhesive layer 160 in this embodiment may include a
thermal curing adhesive, an ultraviolet (UV) curing adhesive, a liquid
optical clear adhesive (OCA), or a pressure sensitive adhesive (PSA), but
not limited thereto. The covering substrate 170 may include a cover lens
or a cover glass so as to protect each component in the touch panel 102,
but not limited thereto. Apart from the adhesive layer 160 and the
covering substrate 170 in this embodiment, the other components,
allocations, material properties, and methods of tuning the thickness and
the refraction index of each layer in this embodiment are similar to
those of the touch panel 101 in the first preferred embodiment detailed
above and will not be redundantly described. It is worth noting that, in
this embodiment, a refraction index of the covering substrate 170 is
smaller than the refraction index of the optical compensation layer 151,
and a refraction index of the adhesive layer 160 is smaller than the
refraction index of the optical compensation layer 151 so as to generate
a better optical effect. More specifically, a relationship of the
refraction indexes between the optical compensation layer 151, the first
axis sensing electrode 121, the adhesive layer 160, and the covering
substrate 170 may be referred in equation (I) listed below, wherein a
refraction index N stands for the refraction index of the optical
compensation layer 151, a refraction index N1 stands for the refraction
index of the first axis sensing electrode 121, a refraction index N2
stands for the refraction index of the adhesive layer 160, and a
refraction index N3 stands for the refraction index of the covering
substrate 170.

N2≦N3<N≦N1 (I)

[0024] The issue of the visible transparent sensing electrodes in the
touch panel may be improved by tuning the material of each layer
according to the equation (I), but not limited thereto. Additionally, the
touch panel 102 in this embodiment and the touch panel 101 in the first
preferred embodiment may be regarded as a kind of single ITO (SITO) touch
panel.

[0025] Please refer to FIG. 4. FIG. 4 is a schematic diagram illustrating
a touch panel according to a third preferred embodiment of the present
invention. As shown in FIG. 4, a touch panel 201 in this embodiment
includes a substrate 210, a touch sensing electrode 220, and an optical
compensation layer 250. The difference between the touch panel 201 of
this embodiment and the touch panel 101 of the first preferred embodiment
is that the touch sensing electrode 220 in this embodiment includes a
first axis sensing electrode 221 and a second axis sensing electrode 222
respectively disposed on two opposite surfaces of the substrate 210. The
first axis sensing electrode 221 and the second axis sensing electrode
222 are stripe pattern electrodes. More specifically, the first axis
sensing electrode 221 is disposed on a first surface 211 of the substrate
210, and the second axis sensing electrode 222 is disposed on a second
surface 212 of the substrate 210. Additionally, the optical compensation
layer 250 includes a first optical compensation layer 251 and a second
optical compensation layer 252. The first optical compensation layer 251
is disposed on the first surface 211 of the substrate and covers the
first axis sensing electrode 221. The second optical compensation layer
252 is disposed on the second surface 212 of the substrate 210 and covers
the second axis sensing electrode 222. In this embodiment, a refraction
index of the optical compensation layer 250 is smaller than or equal to a
refraction index of the touch sensing electrode 220, i.e. a refraction
index of the first optical compensation layer 251 is smaller than or
equal to a refraction index of the first axis sensing electrode 221, and
a refraction index of the second optical compensation layer 252 is
smaller than or equal to a refraction index of the second axis sensing
electrode 222. For example, the refraction index of the first axis
sensing electrode 221 is between 1.7 and 2.0, the refraction index of the
second axis sensing electrode 222 is between 1.7 and 2.0, the refraction
index of the first optical compensation layer 251 is between 1.6 and 1.7,
and the refraction index of the second optical compensation layer 252 is
between 1.6 and 1.7. In addition, the refraction index of the first axis
sensing electrode 221 may be substantially equal to the refraction index
of the second axis sensing electrode 222, and the refraction index of the
first optical compensation layer 251 may be substantially equal to the
refraction index of the second optical compensation layer 252, but the
present invention is not limited to this. The first axis sensing
electrode 221 and the second axis sensing electrode 222 with different
refraction indexes, or the first optical compensation layer 251 and the
second optical compensation layer 252 with different refraction indexes
may also be employed in other preferred embodiments of the present
invention. It is worth noting that a thickness T3 of the first axis
sensing electrode 221 is preferably between 18 nanometers and 150
nanometers, a thickness T4 of the second axis sensing electrode 222 is
preferably between 18 nanometers and 150 nanometers, a thickness T5 of
the first optical compensation layer 251 covering the first axis sensing
electrode 221 is preferably between 60 nanometers and 150 nanometers, and
a thickness T6 of the second optical compensation layer 252 covering the
second axis sensing electrode 222 is preferably between 60 nanometers and
150 nanometers, but not limited thereto. In other preferred embodiments
of the present invention, the thickness of the touch sensing electrode
220 may be larger than 90 nanometers, but not limited thereto.
Additionally, a relationship between the thickness T3 of the first axis
sensing electrode 221 and the thickness T5 of the first optical
compensation layer 251 covering the first axis sensing electrode 221 and
a relationship between the thickness T4 of the second axis sensing
electrode 222 and the thickness T6 of the second optical compensation
layer 252 covering the second axis sensing electrode 222 are similar to
those in the first preferred embodiment detailed above and will not be
redundantly described. In addition, the first optical compensation layer
251 and the second optical compensation layer 252 in this embodiment may
include organic materials, such as polyimide and acrylic resin, inorganic
materials, such as titanium oxide, a single layer structure of the
above-mentioned materials, or a stack layer of the above-mentioned
materials. The first optical compensation layer 251 and the second
optical compensation layer 252 may be formed by dry coating methods, such
as chemical vapor deposition, or wet coating methods, such as spin on
coating, but not limited thereto. The thickness of the second optical
compensation layer 252 may be equal to the thickness of the first optical
compensation layer 251, and the materials of the second optical
compensation layer 252 may be identical to the materials of the first
optical compensation layer 251, but the present invention is not limited
to this, and the first optical compensation layer 251 and the second
optical compensation layer 252 with different materials and different
thicknesses may also be employed in other embodiments of the present
invention. Apart from the second optical compensation layer 252 and the
allocations of the first axis sensing electrode 221 and the second axis
sensing electrode 222 in this embodiment, the other components,
allocations, material properties, and methods of tuning the thickness and
the refraction index of each layer in this embodiment are similar to
those of the touch panel 101 in the first preferred embodiment detailed
above and will not be redundantly described. Additionally, in this
embodiment, an insulating film (not shown) may be selectively disposed
between the substrate 210 and the first axis sensing electrode 221, and
another insulating film (not shown) may be selectively disposed between
the substrate 210 and the second axis sensing electrode 222 so as to
improve the touch operations on the touch panel 201, but not limited
thereto.

[0026] Please refer to FIG. 5. FIG. 5 is a schematic diagram illustrating
a touch panel according to a fourth preferred embodiment of the present
invention. As shown in FIG. 5, the difference between a touch panel 202
of this embodiment and the touch panel 201 of the third preferred
embodiment is that the touch panel 202 further includes two adhesive
layers (one adhesive layer 261 and one adhesive layer 262), a covering
substrate 270, and a protection layer 280. The two adhesive layers are
respectively disposed on the first optical compensation layer 251 and the
second optical compensation layer 252. The covering substrate 270 and the
protection layer 280 are respectively disposed on the two adhesive
layers. In other words, the adhesive layer 261 and the covering substrate
270 are disposed on the first surface 211 of the substrate 210, and the
adhesive layer 262 and the protection layer 280 are disposed on the
second surface 212 of the substrate 210. The adhesive layer 261 is
employed to combine the covering substrate 270 and the first optical
compensation layer 251, and the adhesive layer 262 is employed to combine
the protection layer 280 and the second optical compensation layer 252.
In this embodiment, a refraction index of the adhesive layers is smaller
than the refraction index of the optical compensation layer 250, i.e. a
refraction index of the adhesive layer 261 is smaller than the refraction
index of the first optical compensation layer 251, and a refraction index
of the covering substrate 270 is smaller than the refraction index of the
first optical compensation layer 251. The adhesive layer 261 and the
adhesive layer 262 may include thermal curing adhesives, ultraviolet
curing adhesives, liquid optical clear adhesives, or pressure sensitive
adhesives, but not limited thereto. The protection layer 280 in this
embodiment may include plastics, such as polyethylene terephthalate
(PET), polyethersulfone (PES), polyimide (PI), polycarbonate (PC),
polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), glass, or
the materials mentioned above coated with organic or inorganic functional
coatings, but not limited thereto. Apart from the adhesive layer 261, the
adhesive layer 262, the covering substrate 270, and the protection layer
280 in this embodiment, the other components, allocations, material
properties, and methods of tuning the thickness and the refraction index
of each layer in this embodiment are similar to those of the touch panel
201 in the third preferred embodiment detailed above and will not be
redundantly described. It is worth noting that the touch panel 201 in the
third preferred embodiment and the touch panel 202 in this embodiment may
be regarded as a kind of double ITO (DITO) touch panel because the first
axis sensing electrode 221 and the second axis sensing electrode 222 are
disposed on different surfaces of the substrate 210 in the touch panel
202 of this embodiment and the touch panel 201 in the third preferred
embodiment detailed above.

[0027] Please refer to FIG. 6 and FIG. 7. FIG. 6 and FIG. 7 are schematic
diagrams illustrating a touch panel according to a fifth preferred
embodiment of the present invention. FIG. 6 is a top-view diagram. FIG. 7
is a cross-sectional view diagram taken along a cross-sectional line B-B'
in FIG. 6. As shown in FIG. 6 and FIG. 7, the difference between a touch
panel 301 of this embodiment and the touch panel 101 of the first
preferred embodiment is that, in the touch panel 301 of this embodiment,
the first axis sensing electrodes 121, the second axis sensing electrodes
122, the first connecting line 141, the second connecting line 142, the
insulating layer 130, and the optical compensation layer 151 are all
disposed on a second surface 312 of a substrate 310. A first surface 311
of the substrate 310, which is disposed oppositely to the second surface
312, may be regarded as a touch surface, but not limited thereto.
Additionally, the touch panel 301 in this embodiment further includes a
decoration layer 390 and a conductive line 391. The decoration layer 390
is disposed on an edge of the substrate 310. The decoration layer 390 may
preferably include a ceramic material, a diamond like carbon material, a
color ink, a photo resist or a resin, but not limited thereto. The
conductive line 391 is disposed on the edge of the substrate 310. The
conductive line 391 is electrically connected to the touch sensing
electrode 120, and the touch signals may be transmitted to the touch
sensing electrode 120 through the conductive line 391. The decoration
layer 390 may be used to shield the conductive line 391, but not limited
thereto. Apart from the substrate 310, the decoration layer 390, and the
conductive line 391 in this embodiment, the other components,
allocations, material properties, and methods of tuning the thickness and
the refraction index of each layer in this embodiment are similar to
those of the touch panel 101 in the first preferred embodiment detailed
above and will not be redundantly described. It is worth noting that the
substrate 310 in this embodiment may be a glass substrate or a plastic
substrate, but the present invention is not limited to this. For example,
the substrate 310 may preferably include a cover lens or a cover glass.
Compared to the structure of the touch panel 101 in the first preferred
embodiment detailed above, the touch panel 301 in this embodiment may
become relatively thinner and the corresponding manufacturing process may
be simplified because the substrate 310 may be a cover lens or a cover
glass, and no additional covering substrates are required. In addition,
an insulating film (not shown) may be selectively disposed on between the
substrate 310 and the first axis sensing electrode 121 so as to improve
touch operations on the touch panel 301, but not limited thereto.

[0028] Please refer to FIG. 8. FIG. 8 is a schematic diagram illustrating
a touch panel according to a sixth preferred embodiment of the present
invention. As shown in FIG. 8, the difference between a touch panel 302
of this embodiment and the touch panel 301 of the fifth preferred
embodiment is that the touch panel 302 further include an adhesive layer
160 and a protection layer 380 disposed on the second surface 312 of the
substrate 310. The adhesive layer 160 is disposed on the optical
compensation layer 151, and the protection layer 380 is disposed on the
adhesive layer 160. In other words, the adhesive layer 160 is disposed
between the optical compensation layer 151 and the protection layer 380
so as to combine the optical compensation layer 151 and the protection
layer 380. The protection layer 380 in this embodiment may include
plastics, such as polyethylene terephthalate, polyethersulfone,
polyimide, polycarbonate, polyethylene naphthalate, polymethyl
methacrylate, glass, or the materials mentioned above coated with organic
or inorganic functional coatings, but not limited thereto. The adhesive
layer 160 in this embodiment may include a thermal curing adhesive, an
ultraviolet curing adhesive, a liquid optical clear adhesive, or a
pressure sensitive adhesive, but not limited thereto. It is worth noting
that, in this embodiment, a refraction index of the adhesive layer 160 is
smaller than the refraction index of the optical compensation layer 151
so as to generate better optical effect. Apart from the adhesive layer
160 and the protection layer 380 in this embodiment, the other
components, allocations, material properties, and methods of tuning the
thickness and the refraction index of each layer in this embodiment are
similar to those of the touch panel 301 in the fifth preferred embodiment
detailed above and will not be redundantly described.

[0029] To summarize the above descriptions, in the present invention, at
least one optical compensation layer is disposed in the touch panel, and
the refraction index and the thickness of the optical compensation layer
may be adjusted to the touch sensing electrode so as to overcome the
issue of the visible touch sensing electrodes in the touch panel, which
may be generated by increasing the thickness of the touch sensing
electrode. The total transmittance of the touch panel may also be
increased by the optical compensation layer, and the appearance quality
of the touch panel may be accordingly enhanced.

[0030] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made while
retaining the teachings of the invention. Accordingly, the above
disclosure should be construed as limited only by the metes and bounds of
the appended claims.